This is a discussion on misfire again within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; i keep getting a 2 and 4 misfire at random. it will come on at any time. high rpm, low, ...

misfire again

i keep getting a 2 and 4 misfire at random. it will come on at any time. high rpm, low, in the middle of shifts, or at an idle. it will turn off after 10 key cycles and sometimes stay off for a few days to a week. or a few minutes. my plugs are fairly new, coilpacks are alright, same with compression. i dont think it would be my injectors, cause if it was wouldnt it be a steady misfire? possible fuel pressure regulator? my fp sits at about 42.5 at an idle which is a bit high or pump? im stuck.

You don't really give any information to go on. Is there a CEL? Did you pull the code? What year is your car and what mods does it have?

i dont mean to be an ass but i wouldnt know it was cylinder 2 and 4 with out a cel... p0302 and p0304. 02' wagon, sti top mount, pink injectors, invidia? cated dp, some **** ass header that im about to get rid of, unsure of up pipe(havent touched it, could be stock could be not) and im assuming walbro pump.

im going to see if have have a vac/boost tomarrow if i have time.

i only hit about 12psi yesterday and with the tune i just got it should be about 18-20. not only that built up reeealllllly slow.

hmmm, I would test for boost leaks, get a end cap to a pvc pipe that is small enough to clamp your turbo hose, then take the end off an air tool, grinder or impact gun will work. Drill a hole and fasten the air fitting to it, jb weld is awesome. Now all you have to do is put it in place of the turbo and charge it with air,Tada! you will get some leak down due to the piston rings and an open valve or two. if you have any leak you will be able to hear it pretty well.

hmmm, I would test for boost leaks, get a end cap to a pvc pipe that is small enough to clamp your turbo hose, then take the end off an air tool, grinder or impact gun will work. Drill a hole and fasten the air fitting to it, jb weld is awesome. Now all you have to do is put it in place of the turbo and charge it with air,Tada! you will get some leak down due to the piston rings and an open valve or two. if you have any leak you will be able to hear it pretty well.

how big of a cap is it about 2"? and what kind of pressure? though im sure with any decent amount i would hear a leak. i read on p&ls web site to plug off the evaporating purge lines.... is that a must? and if its where the deuce are they?

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